The process of evolution drives the diversity and unity of life. BIG IDEA #1

 Natural selection acts on phenotypic variations in populations  Sources of variation:  Mutation  Random assortment during meiosis  Crossing Over  Random Fertilization  Diploidy  Allele Frequencies can be altered by:  Gene Flow: Immigration and Emigration  Genetic Drift: small populations  Mating Patterns: Inbreeding and Sexual Selection MECHANISMS OF VARIATION

 Stabilizing Selection: favors intermediate phenotype (heterozygote advantage)  Directional Selection: favors one extreme over another  Disruptive Selection: favors both extremes over the intermediate TYPES OF SELECTION Campbell, Neil A. Reece; Jane B., BIOLOGY, 6 th Edition 2002

 Convergent Evolution: two dissimilar populations evolve similar traits b/c of similar selective pressures. Ex: dolphin and shark  Parallel Evolution: similar to convergent however, organisms do not need to occupy the same niches. Ex: warning colors of many organisms  Divergent Evolution: organisms from a common ancestor become less similar (adaptive radiation) Ex: Galapagos Tortois PATTERNS OF EVOLUTION

 DNA  Amino acid sequence/similar proteins  Analogous structures  Vestigial structures  Homologous structures EVIDENCE FOR EVOLUTION

 Large population  Random mating  No mutations  No gene flow  No natural selection CONDITIONS FOR HARDY-WEINBERG EQUILIBRIUM

 Frequency of dominant allele if frequency of recessive allele is given  p if q is given  Frequency of recessive allele if the % of the population with the recessive phenotype is given  q if q 2 is given  Calculate the % of the population with recessive allele if the % of the population expressing the dominant allele is given  q 2 if p 2 +2pq DETERMINING ALLELE FREQUENCIES

 Speciation occurs when populations accumulate enough changes over time to lead to the emergence of a new species.  Types:  Allopatric—geographic barriers  Sympatric—reproductive barriers  Polyploidy in plants leads to new species b/c the polyploids can not breed with the diploid ancestors SPECIATION

 Prezygotic Isolating Mechanisms:  Geographic (Habitat) Isolation  Ecological Isolation  Behavioral Isolation  Temporal Isolation  Mechanical Isolation  Sexual Isolation  Postzygotic Isolating Mechanisms:  Hybrid Sterility  Hybrid Inviability  Zygote Mortality MECHANISMS FOR REPRODUCTIVE ISOLATION

PRE AND POST ZYGOTIC MECHANISMS FOR REPRODUCTIVE ISOLATION

 Miller and Urey’s Experiment  Amino acid monomers, polymers, protobiont, first cells  Characteristics of the First Cells  Unicellular  Heterotrophic  Prokaryotic  Simple lipid membrane  Ribosomes  RNA  Autotrophic prokaryotes would appear soon after ORIGINS OF LIFE

 Theory of Endosymbiosis— Large eukaryotic cells evolved when a small prokaryotic cells was engulfed by a larger prokaryotic cell and they developed a symbiotic relationship where both benefitted.  Smaller one eventually evolves into mitochondria (in heterotrophs) or chloroplasts (in autotrophs).  Evidence: Mitochondria and Chloroplasts have their own DNA and ribosomes. They are about the size of prokaryotes. Their membranes are similar to prokaryotes. ORIGINS OF COMPLEX CELLS

 Three Domains  Bacteria  Archae  Eukarya  Six Kingdoms  Eubacteria  Archaebacteria  Protista  Fungi  Plantae  Animalia DIVERSITY OF LIFE

 Cladograms show relative relatedness between a group of organisms CLADOGRAMS